• Title/Summary/Keyword: water spray system

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A study on spray characteristics of the triplet impinging stream type injector for liquid rocket (액체 로켓용 충돌형 Triplet 인젝터의 미립화 특성에 관한 연구)

  • Park, Sung-Young;Kim, Seon-Jin;Park, Seung-Woon;Kim, Yoo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.20 no.3
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    • pp.1005-1014
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    • 1996
  • An experimental investigation has been carried out to examine the influence of injector design variables and operating conditions on the resultant drop size for triplet impinging streams injectors. The variables studied in this investigation are pressure drop, impinging angle, orifice length to diameter ratio, and impinging point distance. Droplet-size data are obtained using water as the propellant simulant by Malvern Particle Analyzer System. Drop size decreases with increasing impinging angle and pressure drop while other injector parameters remain constant at the same point. But it is found that there is no noticeable droplet-size change which results from change in orifice length to diameter ratio or impinging point distance within the investigated range.

Size Distribution of Droplets Sprayed by an Orchard Sprayer (과수방제기 살포입자의 직경 분포특성)

  • 구영모;신범수;김상헌
    • Journal of Biosystems Engineering
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    • v.26 no.5
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    • pp.431-440
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    • 2001
  • Generated agri-chemical droplets by orchard sprayers are evaporated regenerated and transported along wind streams. The droplets are deposited to targets after changing their sizes, affecting the retention of droplets. An orchard sprayer, designed for spraying grapevines was studied on the spatial distribution of droplet size. The experimental variables were spray direction (0, 22.5, 45, 67.5 and 90˚), distance(2.5, 3.0 and 3.5 m) and fan speed (2,075 and 3,031 rpm). Droplet sizes were converted and analyzed from spray stains, sampled using water sensitive papers. The number median diameter (NMD) increased with an increase of the distance due to disappeared fine droplets (<50 ㎛): however, the volume median diameter (VMD) decreased due to shrunken large droplets (>100 ㎛). Fast fan speed delivered large droplets to 3.5 m, but the spatial distributions of NMD and VMD were not uniform. Slower fan speed decreased the possibility of evaporation and drift; therefore, plenty of droplets were maintained up to 3.0 m. The upward blasting distance was limited within 3 m, but the limit to the ground level was extended to 3.5 m. Concentrated wind and droplets to the ground level should be redistributed to upper canopy direction, leading more uniform deposits. High speed wind and system pressure should be avoided because of generating fine droplets, which would be disappeared and drifted away.

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Experimental Investigation of Collision Mechanisms Between Binary Droplet of Fuel Jet (연료 제트의 두 액적간의 충돌기구에 관한 실험적 연구)

  • Lee, Keun-Hee;Kim, Sa-Yop;Lee, Chang-Sik
    • Journal of ILASS-Korea
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    • v.13 no.4
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    • pp.187-192
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    • 2008
  • In this study, the mechanisms of binary droplet collision were studied with diesel, ethanol and purified water. The droplet collisions of liquid droplet have been investigated for the same droplet diameter. In order to obtain the digital images of the droplet collision behavior, the experimental equipment was composed of the droplet generating system and the droplet visualization system. The droplets were produced by the vibrating orifice monodisperse generator. The visualization system consisted of a long distance microscope, a light source, and a high speed camera. The outcomes of binary droplet collision can be divided into four regimes, bouncing, coalescence, reflexive separation and stretching separation. The impact angle and the relative velocity of binary droplet are main parameters of collision phenomena, so the transition mechanism of droplet collision can be divided by the impact parameter.

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Effective Control of fine Particles Using an Electrostatic Coagulation Between Particle and Water Droplet (입자와 액적간의 정전기적 응집을 통한 미세입자의 효율적인 제어)

  • Lee, Myong-Hwa;Kim, Sang-Bum;Hwang, You-Seong;Kim, Jong-Ho;Kim, Gyung-Soo
    • Journal of ILASS-Korea
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    • v.11 no.2
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    • pp.98-104
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    • 2006
  • A charged droplet scrubber was introduced to remove visible smokes generated in many industrial facilities. Lab-scale and field tests were conducted in this study. The system consists of a corona discharger to effectively charge the fine particles, fellowed by an electrostatic chamber to promote coagulation between charged fine particles and oppositely charged droplets and a demister to remove resultant particles. Overall collection efficiency, 98.4% was obtained from a lab-scale test, when a high voltage was applied to an ionizer and a charged droplet scrubber. Field tests also show the high collection efficiencies, 93.5% with one stage and 99.4% with two stage system. This system can be used to increase the collection efficiency of the conventional air pollution control devices to satisfy the national emission standard.

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Evaluation of Thermal Utilization of Dousing System in PHWR Nuclear Power Plant

  • Nam, S.D.;Ryu, J.I.
    • Journal of ILASS-Korea
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    • v.4 no.3
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    • pp.42-52
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    • 1999
  • An effectiveness of thermal utilization of a dousing system in the 600 MW PHWR Nuclear Power Plant has been evaluated. The behavior and conditions of water droplet sprayed in a postulated accident conditions in containment configuration has been calculated. In this calculation, two pressure conditions with the consideration of obstruction area and containment wall effect has been established : one being the minimum containment pressure of 7 kPa(g) encountered for dousing shut off and the other being the containment design pressure 124 kPa(g). The results revealed that the effectiveness of the thermal utilization ranges from 93% to 97%. In the analysis on two cases without/with side wall effect in the containment building, the thermal utilization decreases with obstruction area from 89% to 85%, which satisfies the design criteria set for the containment pressure against the accident condition.

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Critical heat flux measurement experiment to improve safety of copper nano-particle coated heat exchanger (구리나노입자가 코팅된 열교환기의 안전성 향상을 위한 임계 열유속 측정실험)

  • Mo, Yong-Hyun;Kim, Nam-Jin;Jeon, Yong-Han;Lee, Deok-Soo
    • Journal of the Korea Safety Management & Science
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    • v.19 no.4
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    • pp.317-322
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    • 2017
  • When the heat flux on the heating surface following changing heat condition in the boiling heat transfer system exceeds critical heat flux, the critical heat flux phenomenon is going over to immediately the film boiling area and then it is occurred the physical destruction phenomenon of various heat transfer systems. In order to maximize the safe operation and performance of the heat transfer system, it is essential to improve the CHF(Critical Heat Flux) of the system. Therefore, we have analysis the effect of improving CHF and characteristics of heat transfer following the nanoparticle coating thickness. As the results, copper nanocoating time are increased to CHF, and in case of nano-coatings are increased spray-deposited coating times more than in the fure water; copper nanopowder is increased up to 6.40%. The boiling heat transfer coefficients of the pure water are increased up to 5.79% respectively. Also, the contact angle is decreased and surface roughness is increased when nano-coating time is increasingly going up.

Experimental Investigation on the Thermal Performance Enhancement of Cooling System for Vehicles using Water/Coolant-Based Al2O3 Nanofluids (물/부동액-기반Al2O3나노유체를 이용한 차량용 냉각시스템 성능 향상에 관한 실험적 연구)

  • Park, Y.-J.;Kim, H.J.;Lee, S.-H.;Choi, T.J.;Kang, Y.J.;Jang, S.P.
    • Journal of ILASS-Korea
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    • v.20 no.2
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    • pp.65-69
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    • 2015
  • In this study, the thermal performance of vehicle's cooling system is experimentally investigated using the water/coolant-based $Al_2O_3$ nanofluids as working fluids. For the purpose, the water/coolant-based $Al_2O_3$ nanofluids are prepared by twostep method with gum arabic. In order to obtain the well-suspended nanofluids, the agglomerated $Al_2O_3$ nanoparticles are precipitated using centrifugal force and the experiments are performed with supernatant of them. The thermal conductivity is measured by transient hot wire method and the thermal conductivity of nanofluids is enhanced up to 4.8% as compared to that of base fluids. Moreover, the cooling performance of water/coolant-based $Al_2O_3$ nanofluids is evaluated using vehicle's engine simulator under the constant RPM condition. The results show that the cooling performance of automobile engine increases up to 5.9% using prepared nanofluids. To investigate the effect of nanofluids on exhaust gas, the $NO_x$ emission is measured during the operation with respect to time and 10.3% of $NO_x$ emission is decreased. The experimental results imply that the water/coolant-based $Al_2O_3$ nanofluids might be used as a next-generation vehicles' coolant

Fabrication of Metallic Particle Dispersed Ceramic Based Nanocomposite Powders by the Spray Pyrolysis Process Using Ultrasonic Atomizer and Reduction Process

  • Choa, Y.H.;Kim, B.H.;Jeong, Y.K.;Chae, K.W.;T.Nakayama;T. Kusunose;T.Sekino;K. Niibara
    • Journal of Powder Materials
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    • v.8 no.3
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    • pp.151-156
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    • 2001
  • MgO based nanocomposite powder including ferromagnetic iron particle dispersions, which can be available for the magnetic and catalytic applications, was fabricated by the spray pyrolysis process using ultra-sonic atomizer and reduction processes. Liquid source was prepared from iron (Fe)-nitrate, as a source of Fe nano-dispersion, and magnesium (Mg)-nitrate, as a source of MgO materials, with pure water solvent. After the chamber were heated to given temperatures (500~$^800{\circ}C$), the mist of liquid droplets generated by ultrasonic atomizer carried into the chamber by a carrier gas of air, and the ist was decomposed into Fe-oxide and MgO nano-powder. The obtained powders were reduced by hydrogen atmosphere at 600~$^800{\circ}C$. The reduction behavior was investigated by thermal gravity and hygrometry. After reduction, the aggregated sub-micron Fe/MgO powders were obtained, and each aggregated powder composed of nano-sized Fe/MgO materials. By the difference of the chamber temperature, the particle size of Fe and MgO was changed in a few 10 nm levels. Also, the nano-porous Fe-MgO sub-micron powders were obtained. Through this preparation process and the evaluation of phase and microstructure, it was concluded that the Fe/MgO nanocomposite powders with high surface area and the higher coercive force were successfully fabricated.

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Optimization of Fugitive Dust Control System for Meteorological Conditions (기상조건별 비산먼지 관리체계 최적화 연구)

  • Kim Hyun-Goo
    • Journal of Korean Society for Atmospheric Environment
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    • v.21 no.6
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    • pp.573-583
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    • 2005
  • Fugitive dust, which is emitted in the ambient air without first passing through a stack or duct designed to control flow, is frequently generated by means of wind erosion from storage yards at Pohang Steel Wokrs. The size distribution of fugitive dust is mostly in the range of coarse particulate which is deposited as soon as emitted and less harm to human health; however $20\%$ of fugitive dust contains PM 10 known as one of most harmful airborne pollutant. Consequently, effective control and reduction of fugitive dust is strongly requested by the local society, but it is not easy so far because the generation and dispersion of fugitive dust highly depends on meteorological conditions, and it being occurred for irregularity. This research presented a fugitive dust control system for each meteorological condition by providing statistical prediction data obtained from a statistical analysis on the probability of generating the threshold velocity at which the fugitive dust begins to occur, and the frequency occurring by season and by time of the wind direction that can generate atmospheric pollution when the dispersed dust spreads to adjacent residential areas. The research also built a fugitive dust detection system which monitors the weather conditions surrounding storage yards and the changes in air quality on a real-time basis and issues a warning message by identifying a situation where the fugitive dust disperses outside the site boundary line so that appropriate measures can be taken on a timely basis. Furthermore, in respect to the spraying of water to prevent the generation of fugitive dust from the storage piles at the storage yard, an advanced statistical meteorological analysis on the weather conditions in Pohang area and a case study of fugitive dust dispersion toward outside of working field during $2002\∼2003$ were carried out in order to decide an optimal water-spraying time and the number of spraying that can prevent the origin of fugitive dust emission. The results of this research are expected to create extremely significant effects in improving surrounding environment through actual reduction of the fugitive dust produced from the storage yard of Pohang Steel Works by providing a high-tech warning system capable of constantly monitoring the leakage of fugitive dust and water-spray guidance that can maximize the water-spraying effects.

Computational Analysis on the Control of Droplet Entrained in the Exhaust from the Spray Type Scrubber system (스프레이형 스크러버의 배출가스에 포함된 액적의 제어방법에 관한 전산해석적 연구)

  • Lee, Chanhyun;Chang, Hyuksang;Koo, Seongmo
    • Clean Technology
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    • v.21 no.3
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    • pp.191-199
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    • 2015
  • The SOx emission from the ship diesel engines will do a negative influence to the human health and the environment. To reduce the negative environmental effect of the SOx emission caused by the high traffic of ship movements, the SECA (SOx emission control area) has been set on several province around world to carry out the severe emissions control and to meet the emissions control standard. To cut down the SOx emission from the ships, the wet type scrubber is being used widely. In this work, we prepared a numerical model to simulate the spray type scrubber to study the motion of liquid droplets in the flow of the scrubber. For the analysis, the CFD (computational fluid dynamics) method was adopted. As a special topic of the study, we designed the wave plate type of mist eliminator to check the carry over of the uncontrolled water droplet to the exhaust. Numerical analysis is divided into two stages. At the first stage, the analysis was done on the basic scrubber without the mist eliminator, and then the second stage of analysis was done on the scrubber with the mist eliminator on several condition to check and compare with the basic scrubber. On the condition of the basic scrubber, 42.0% of the distributed water droplets were carried over to the exhaust. But by adding the designed droplet eliminator at the exhaust of the scrubber, only 3.4% of the distributed water droplets supplied to the scrubber was emitted to the atmosphere.